This archive report was first published on 7 January 2022.
Women's Periods May Be Late After Coronavirus Vaccination, Study Suggests ¶
Researchers have found that women's menstrual cycles may be affected by coronavirus vaccination, with some experiencing late or irregular periods.
According to a study published in January 2022, women who received the coronavirus vaccine experienced a slight delay in their menstrual cycles, with some periods starting up to two days later than usual.
The study, which was conducted by researchers at Oregon Health & Science University and the Warren Alpert Medical School of Brown University, analyzed data from nearly 4,000 women who had tracked their menstruation using an app called Natural Cycles.
The researchers found that women who received both doses of the vaccine during the same menstrual cycle experienced the most significant delay, with their periods starting up to two days later than usual.
However, the study also found that the changes in menstrual cycles were transient and returned to normal within one or two months.
Dr. Hugh Taylor, chair of the department of obstetrics, gynecology and reproductive sciences at Yale School of Medicine, said that the study validated anecdotal reports from women that their menstrual cycles were affected by the vaccine.
“It validates that there is something real here,” Dr. Taylor said. “A cycle or two where periods are thrown off may be annoying, but it’s not going to be harmful in a medical way.”
Dr. Diana Bianchi, director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, said that the study's findings should be reassuring for women in their childbearing years.
“Their providers can say, ‘If you have an extra day, that is normal, it’s not something to be concerned about,’” Dr. Bianchi said.
